#include <stdio.h>

int main() {
    int a[5 ]= {0},i = 0,sum = 0;
    double avg = 0;
    for(i=0;i<5;i++) 
    {
    scanf("%d",&a[i]);
    sum+=a[i];
    }
    avg = sum/5.0;
    printf("%.1lf",avg);
    return 0;
}
